The maximum entropy of an optical spectrum and the redistribution in phase space

The Fourier time transform of an optical spectrum determines the autocorrelation function for a non-stationary state. The entropy of this state is computed using the maximum-entropy formalism. Due to the redistribution of the state over the available phase space, the entropy is time dependent. It is argued that the entropy provides a useful measure for the volume in phase space which has been sampled up to the time t. The maximal value of the entropy determines the volume which can be accessed in the long-time limit of the dynamics.